By default Exchange Management Console and Exchange Management Shell has the recipient scope in same domain where Exchange server or Exchange Management tools installed computer.
You may need to change it to entire forest using this cmdlet, then try Get-RoleGroup.
Set-AdServerSettings -ViewEntireForest $True -PreferredGlobalCatalog gc1.yak.com
You may try the following command as
Get-RoleGroup -ReadFromDomainController “Primary GC FQDN”